hair usually grows about 0.5 to 1 inch a month, so over a year it would be about 6 inches/ 12 inches longer but it depends on things like your diet etc, if its bad your hair doesnt get enough nutrients so it doesnt grow as much. if you want your hair to grow faster im using a shampoo called FAST - fortified amino scalp treatment, its really good my hair has grown about 3.5 inches in the last couple of months! i recommend it :D